An inkjet printer forms a printed image by printing a pattern of individual dots at particular locations of an array defined for the printing medium. The locations may be visualized as being small dots in a rectilinear array. The locations are sometimes called “dot locations,” “dot positions,” or “pixels.” Thus, a printing operation can be viewed as providing a pattern of dot locations with dots of ink.
Inkjet printers print pixels by ejecting drops of ink from ink ejecting nozzles onto the print medium and typically include a movable print carriage that supports one or more print cartridges. The print carriage traverses axially above the surface of the print medium, while the nozzles are controlled to eject drops of ink at appropriate times pursuant to command of a microcomputer or other controller. The timing of the application of the ink drops is intended to correspond to the pattern of pixels of the image being printed.
The particular ink ejection mechanism within the printhead may take on a variety of different forms known to those skilled in the art, such as those using thermal ejection or piezoelectric technology. For instance, two exemplary thermal ejection mechanisms are shown in commonly assigned U.S. Pat. Nos. 5,278,584 and 4,683,481. In a thermal ejection system, an ink barrier layer containing ink channels and ink vaporization chambers is disposed between a nozzle orifice plate and a thin film substrate. The thin film substrate typically includes arrays of heater elements such as thin film resistors which are selectively energized to heat ink within the vaporization chambers. When the heater elements are energized, an ink droplet is ejected from a nozzle associated with the heater element. By selectively energizing heater elements, ink drops are ejected onto the print medium in a pattern to form the desired image.
Certain inkjet printers employ replaceable print cartridges, and a consideration with such printers is the need for a reliable electrical interface between a print cartridge and the printer in which it is installed.